Image-based Calibration.
To obtain a coarse calibration, we first perform image-based calibration following the general steps in Zhang's method [1]}. However, we highlight that Kinect's active IR depth cameras encounter over-exposure with regular chessboards. Hence, we customize a light absorbent material to cover the black squares of the chessboard pattern. In this way, we acquire reasonably accurate extrinsic calibration for Kinects and iPhones.
